JPH07294042A - Refrigerator - Google Patents

Abstract

PURPOSE:To provide a refrigerator (air conditioner) in which subcooling can be detected and controlled even when nonazeotropic refrigerant having a temperature glide is used. CONSTITUTION:A refrigerator uses non-azeotropic refrigerant and comprises a fixed resistor 16 located at an outlet of a heat exchanger 15 to apply predetermined resistance to the refrigerant when the exchanger 15 is operated as a condenser, first and second temperature sensors 40, 42 located at the front and rear of the resistor 16 to detect the change of the temperature due to the resistor 16. Thus, even if the non-azeotropic refrigerant is used as refrigerant, subcooling can be detected and controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus, and particularly to a subcool (SC) control when a condenser is provided and a single refrigerant or a non-azeotropic mixed refrigerant composed of a high boiling point refrigerant and a low boiling point refrigerant is used. The present invention relates to a refrigerating device (air conditioner) capable of performing.

[0002]

2. Description of the Related Art Generally, a refrigerant circuit of a heat pump type air conditioner includes a compressor 1, an indoor heat exchanger 2, a flow control valve 3, an outdoor heat exchanger 4, a four-way valve 5, etc., as shown in FIG. It is configured, as shown by the solid arrow during heating operation,
The refrigerant is circulated in this order, and during the cooling operation, the refrigerant circulates in the opposite direction to that during the heating operation.

By switching the operation as described above, the cooling operation and the heating operation are performed by one circuit.

On the other hand, in such a heat pump type air conditioner, when a single refrigerant (for example, R-22) is used as the refrigerant, the pressure of the single refrigerant is constant and at the time of gas-liquid mixing. The temperature of the refrigerant becomes constant, and the inlet temperature and the outlet temperature in the indoor heat exchanger 2 can be made equal.

That is, as shown in the Mollier diagram shown in FIG. 7, if the pressure of a single refrigerant is constant, the saturation pressure is also constant,
Since there is no temperature gradient between the inlet side and the outlet side of the indoor heat exchanger 2, that is, there is no temperature glide, it is possible to measure the intermediate temperature (condensation temperature) at any part of the indoor heat exchanger 2. Can also be used as the condensation temperature.

[0006] In this indoor heat exchanger 2, when the cooling efficiency of the indoor heat exchanger 2 is observed from the supercooling, the condensation temperature T11 in the indoor heat exchanger 2 shown in FIG. 6 and the outlet of the indoor heat exchanger 2 are shown. From the temperature difference from the temperature T12, supercooling (subcool SC = condensation temperature T11−outlet temperature T12) was detected, and the refrigerant circuit in FIG. 6 was subjected to subcool control.

[0007]

However, when a non-azeotropic mixed refrigerant composed of a high boiling point refrigerant and a low boiling point refrigerant is used as the refrigerant in the refrigerant circuit of FIG. 6, instead of a single refrigerant,
Since the refrigerant having a low boiling point evaporates first, it differs from the Mollier diagram in the case of using the single refrigerant in FIG. 7. That is, when the pressure of the non-azeotropic mixed refrigerant is constant and the gas-liquid mixing is performed, the isotherm of the non-azeotropic mixed refrigerant is descending to the right from the saturated liquid line to the saturated vapor line (temperature glide: About 5 °
C).

Due to this temperature glide, the intermediate temperature of the indoor heat exchanger 2 is not always the condensation temperature of the indoor heat exchanger 2. That is, when the non-azeotropic mixed refrigerant is used, the correct condensation temperature of the indoor heat exchanger 2 cannot be detected.

Therefore, when a non-azeotropic mixed refrigerant is used,
Condensation temperature T11 in the conventional indoor heat exchanger 2 of FIG.
And the temperature difference between the outlet temperature T12 of the indoor heat exchanger 2 and the subcool SC of the indoor heat exchanger 2 cannot be detected to determine whether the refrigerant is in the liquid state or the wet state. was there.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a refrigeration system capable of detecting and controlling a subcool even when a non-azeotropic mixed refrigerant having a temperature glide is used.

[0011]

A first aspect of the present invention is a refrigeration system in which a single refrigerant or a non-azeotropic mixed refrigerant composed of a high boiling point refrigerant and a low boiling point refrigerant is circulated to the heat exchanger. A fixed resistance that is arranged at the outlet of the heat exchanger when working as a condenser, and that imparts a constant flow resistance to the refrigerant,
A first temperature sensor and a second temperature sensor for detecting a change in temperature due to the fixed resistance are provided before and after the fixed resistance.

A second aspect of the present invention is a refrigeration system in which a single refrigerant or a non-azeotropic mixed refrigerant composed of a high boiling point refrigerant and a low boiling point refrigerant is circulated to a heat exchanger, and when the heat exchanger acts as a condenser, A variable resistor that is arranged at the outlet of the heat exchanger and has a variable resistance value that gives a flow path resistance to the refrigerant, and a variable resistor that is arranged before and after the variable resistor to detect a change in temperature due to the variable resistor. And a second temperature sensor.

A third aspect of the present invention is a refrigerating apparatus in which a single refrigerant or a non-azeotropic mixed refrigerant composed of a high boiling point refrigerant and a low boiling point refrigerant is circulated in a heat exchanger, and the refrigerating apparatus is disposed at the outlet of the heat exchanger, A resistor that gives flow resistance to the refrigerant when the heat exchanger functions as a condenser, and a first temperature sensor and a first temperature sensor that are disposed in front of and behind the resistor to detect a temperature change by the resistor. The second temperature sensor and a flow rate control valve that controls the flow rate of the refrigerant according to the detection values of the first and second temperature sensors are provided.

[0014]

According to the first aspect of the invention, when the heat exchanger acts as a condenser, the fixed resistance imparts a constant resistance to the refrigerant, and the first temperature sensor and the second temperature before and after the fixed resistance are applied. The sensor detects the temperature change due to the fixed resistance.
Thereby, the state of the refrigerant at the outlet of the condenser, that is,
Even if the liquid state or the wet state is determined and the non-azeotropic mixed refrigerant is used as the refrigerant, the subcool can be detected and controlled.

According to the second aspect of the invention, when the heat exchanger acts as a condenser, resistance is imparted to the refrigerant by the variable resistance,
The first temperature sensor and the second temperature sensor before and after the variable resistor detect a change in temperature due to the variable resistor. With this, the variable resistor can freely set the temperature difference according to the refrigerant state, so that the subcool can be reliably detected and controlled.

According to the third aspect of the invention, when the heat exchanger acts as a condenser, resistance is imparted to the refrigerant by the resistor, and the first temperature sensor and the second temperature sensor before and after the resistor provide the resistance. , Detects temperature changes caused by resistors. The size of the subcool can be adjusted by adjusting the opening of the flow control valve based on the detection result.

Since the present invention detects the gas-liquid state of the refrigerant, even in the case of a single refrigerant, the subcool can be adjusted as in the case of mixed refrigerant.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a refrigerant circuit diagram of an embodiment according to the refrigerating apparatus of the present invention. The refrigerating apparatus according to this embodiment,
A non-azeotropic mixed refrigerant composed of a high boiling point refrigerant and a low boiling point refrigerant is used as the refrigerant circulating in the refrigerant circuit.

In the refrigerant circuit of FIG. 1, the compressor 13, the indoor heat exchanger 15, the fixed resistance 16, the flow rate control valve 17, the outdoor heat exchanger 19, the four-way valve 31 as a flow path switching valve, and the accumulator 33 are provided. They are arranged in order.

The outdoor heat exchanger 19 and the indoor heat exchanger 15 as heat exchangers each have a fan, and the outdoor air or the indoor air is heat-exchanged.

Indoor heat exchanger 15 and flow control valve (mechanical valve)
Between 17 (the outlet side of the indoor heat exchanger 15 during heating),
The fixed resistor 16 is arranged.

As the fixed resistor 16, for example, one formed in the shape of a thin tube coil or an orifice is used.

The outlet side of the indoor heat exchanger 15 and the fixed resistance 16
The first temperature sensor 40 is arranged between the fixed resistance 16 and the flow control valve 17, and the second temperature sensor 42 is arranged between the fixed resistance 16 and the flow control valve 17.

The four-way valve 31 is positioned so that the refrigerant flows as indicated by the broken line during the cooling operation and is indicated as indicated by the solid line during the heating operation. By switching the four-way valve 31 in this way, the cooling medium passage and the cooling medium passage are switched.

In the heat pump type air conditioner, when the indoor heat exchanger 15 acts as an evaporator during cooling operation, the outdoor heat exchanger 19 acts as a condenser, and during heating operation, When the indoor heat exchanger 15 acts as a condenser, the outdoor heat exchanger 19 acts as an evaporator.

As the non-azeotropic mixed refrigerant, for example, R13
A mixed refrigerant of 4a, R125, and R32 is used. Generally, the boiling point of R134a is -26 degrees Celsius, the boiling point of R125 is -48 degrees Celsius, and the boiling point of R32 is -52 degrees Celsius.

Next, the operation of the above embodiment will be described.

In the refrigerant circuit of FIG. 1, during cooling operation, the four-way valve 31 of FIG. 1 is positioned as shown by the broken line, and the compressor 13, the outdoor heat exchanger 19, the flow control valve 17, the fixed resistor 16, the indoor The refrigerant is circulated in the order of the heat exchanger 15, the four-way valve 31, and the accumulator 33. During this cooling operation,
The outdoor heat exchanger 19 acts as a condenser, the indoor heat exchanger 15 acts as an evaporator, and the refrigerant is vaporized to draw heat from the outside air.

On the other hand, in the refrigerant circuit of FIG. 1, during heating operation, the four-way valve 31 is positioned as shown by the solid line in FIG.
The refrigerant is circulated in the order of the compressor 13, the indoor heat exchanger 15, the fixed resistance 16, the flow control valve 17, the outdoor heat exchanger 19, the four-way valve 31, and the accumulator 33. At this time, the first temperature sensor 40 functions as the indoor heat exchanger 1 acting as a condenser.
The temperature of the refrigerant is detected between the outlet side of 5 and the fixed resistance 16. In addition, the second temperature sensor 42 detects the temperature of the refrigerant between the fixed resistance 16 and the flow control valve 17.

During the heating operation, the refrigerant introduced from the compressor 13 into the indoor heat exchanger 15 exchanges heat with the indoor air.
The refrigerant passing through the indoor heat exchanger 15 acting as a condenser is introduced into the outdoor heat exchanger 19 through the fixed resistance 16 and the flow rate control valve 17, and the outdoor heat exchanger 19 acts as an evaporator, The refrigerant is vaporized and draws heat from the outside air.

During the heating operation, in the indoor heat exchanger 15, as shown in FIG. 2, the non-azeotropic mixed refrigerant composed of the high-boiling point refrigerant and the low-boiling point refrigerant has a low boiling point, so that the non-azeotropic refrigerant is non-azeotropic. The isotherm of the boiling mixed refrigerant descends to the right from the saturated liquid line to the saturated vapor line, and a temperature glide occurs between the inlet side and the outlet side of the indoor heat exchanger 2.

Due to this temperature glide, the intermediate temperature of the indoor heat exchanger 2 is not always the condensation temperature of the indoor heat exchanger 2. That is, the efficient condensation temperature of the indoor heat exchanger 2 cannot be detected.

Therefore, in the embodiment of the present invention, the fixed resistance 16 is provided at the outlet of the indoor heat exchanger 15 which functions as a condenser during the heating operation, and the refrigerant passing through the fixed resistance 16 is in the state of the refrigerant. That is, it is known that the temperature difference around the fixed resistance 16 changes depending on the mixing ratio of the refrigerant liquid and the refrigerant vapor (whether the refrigerant is in a liquid state or in a wet state). Therefore, the temperature difference is detected by the first and second temperature sensors 40 and 42 arranged before and after the fixed resistor 16 to detect whether the outlet side of the indoor heat exchanger 2 is in a wet state or a liquid state or the temperature difference. The value of the subcool SC is adjusted by adjusting the opening degree of the flow control valve 17 based on this.

Here, referring to FIG. 3, the isotherm (AB) of the liquid region of the refrigerant is a line that is almost parallel to the pressure change, and the temperature change at the time of pressure change is small.

On the other hand, the isotherm (B-
Since C) is a line that is almost vertical to the pressure change, the temperature change is large when the pressure changes.

Therefore, when it is desired to change the state of the refrigerant at the outlet of the heat exchanger from the wet state to the liquid state, the saturated liquid line is passed when the temperature difference changes from the large temperature difference to the small temperature difference, and this change amount is detected. By doing so, the state can be detected.

Specific subcool SC control will be described below.

In FIG. 3, T1 indicates the temperature before the fixed resistor 16 and T2 indicates the temperature after the fixed resistor 16.

As shown in FIG. 2, when the subcool SC1 is set to 5 ° C. for a certain circulation amount, the difference between P1 (the pressure before the fixed resistance) and P2 (the pressure after the fixed resistance), that is, ΔP1 Is required to be 1.5 kg / square centimeter. At that time, the difference between the temperature T1 before the fixed resistance and the temperature T2 after the fixed resistance, ΔT, is around 2 ° C.

Further, as shown in FIG. 2, when the subcool SC2 is set to 10 ° C. for a certain circulation amount, P1
The difference between (before pressure of fixed resistance) and P2 (after pressure of fixed resistance), that is, ΔP2, is required to be 2 to 3 kg / square centimeter. At that time, the difference between the temperature T1 before the fixed resistor 16 and the temperature T2 after the fixed resistor 16, ΔT, is around 1 ° C.

ΔT concerning the size of this subcool SC
The relationship between ΔP and ΔP is as shown in FIG. As is clear from FIG. 4, in a refrigeration system using a non-azeotropic mixed refrigerant, ΔT is reduced when a large number of subcool SCs are used,
If subcool SC is not taken too much, increase ΔT.

In the case of the embodiment shown in FIG. 1, since the fixed resistor 16 is used as the resistor, the type of the fixed resistor 16 is selected according to the size of the subcool SC required depending on the size of the indoor heat exchanger. change. Then, by adjusting the opening degree of the flow control valve 17 in FIG. 1 and taking the temperature difference described above, the subcool SC is detected and the refrigerant circuit is subjected to subcool control.

Next, another embodiment according to the present invention will be described with reference to FIG.

In the embodiment shown in FIG. 5, the same parts as those of the embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In the embodiment shown in FIG. 5, a variable resistor 116 is used instead of the fixed resistor 16 used in the embodiment shown in FIG. That is, the indoor heat exchanger 15 and the flow control valve 17
A variable resistor 116 is arranged between them.

The outlet side of the indoor heat exchanger 15 and the variable resistor 11
A first temperature sensor 40 is arranged between 6 and a second temperature sensor 42 is arranged between the variable resistor 116 and the flow control valve 17.

As shown in FIG. 4, when a large amount of subcool SC is taken, ΔT is made small, and when a small amount of subcool SC is taken, ΔT is made large.
The variable resistance (mechanical valve) 116 of the above embodiment is changed. That is, as shown in FIG. 3, the variable resistor 16 is narrowed down from the full opening. The capacitance of the variable resistor 116 is preferably such that the subcool SC becomes zero when fully opened.

The present invention is not limited to the above embodiment,
Various modifications can be made without departing from the scope of the present invention.

For example, the above-described subcool control may be performed on the outlet side of the outdoor heat exchanger that serves as a condenser during cooling.
The heat source can be water as well as air. Further, since the present invention detects the gas-liquid state of the refrigerant, the same effect can be obtained even if a single refrigerant is used as the refrigerant in addition to the non-azeotropic mixed refrigerant.

[0051]

As described above, according to the first aspect of the present invention, when the heat exchanger acts as a condenser, the fixed resistance imparts a constant resistance to the refrigerant, and the first resistance before and after the fixed resistance is applied. The temperature change of the fixed resistance is detected by the temperature sensor and the second temperature sensor. Accordingly, the state of the refrigerant at the outlet of the condenser, that is, the liquid state or the wet state is determined, and the subcool can be detected and controlled even if the non-azeotropic mixed refrigerant is used as the refrigerant.

According to the second invention, when the heat exchanger acts as a condenser, resistance is imparted to the refrigerant by the variable resistance,
The first temperature sensor and the second temperature sensor before and after the variable resistor detect a change in temperature due to the variable resistor. With this, the variable resistor can freely set the temperature difference according to the refrigerant state, so that the subcool can be reliably detected and controlled.

Further, according to the third invention, when the heat exchanger acts as a condenser, the resistance imparts resistance to the refrigerant, and the first temperature sensor and the second temperature before and after the resistance are provided. The sensor detects the temperature change caused by the resistor.
The size of the subcool can be adjusted by adjusting the opening of the flow control valve based on the detection result.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of a refrigeration system (air conditioner) of the present invention.

FIG. 2 is a Mollier diagram in the embodiment of FIG.

FIG. 3 is an enlarged view of the Mollier diagram of FIG.

FIG. 4 is a diagram showing a relationship among temperature, pressure, and subcool.

FIG. 5 is a refrigerant circuit diagram showing another embodiment of the refrigerating apparatus (air conditioner) of the present invention.

FIG. 6 is a refrigerant circuit diagram showing a conventional refrigeration system.

7 is a Mollier diagram in the conventional refrigerating apparatus of FIG.

[Explanation of symbols]

 13 Compressor 15 Indoor Heat Exchanger 16 Fixed Resistance (Resistor) 17 Flow Control Valve (Mechanical Valve) 40 First Temperature Sensor 42 Second Temperature Sensor 116 Variable Resistance (Resistor)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F25B 49/02 C

Claims (3)

[Claims] 1. A refrigeration system in which a single refrigerant or a non-azeotropic mixed refrigerant composed of a high-boiling point refrigerant and a low-boiling point refrigerant is circulated to a heat exchanger, and when the heat exchanger acts as a condenser, A fixed resistance which is arranged at the outlet and gives a constant flow resistance to the refrigerant, and a first temperature sensor and a second temperature sensor which are arranged before and after the fixed resistance for detecting a temperature change due to the fixed resistance. A refrigeration system comprising a temperature sensor. 2. A refrigeration system in which a single refrigerant or a non-azeotropic mixed refrigerant consisting of a high-boiling-point refrigerant and a low-boiling-point refrigerant is circulated in a heat exchanger, and when the heat exchanger acts as a condenser, A variable resistor that is arranged at the outlet and has a variable resistance value that imparts flow path resistance to the refrigerant; and a first temperature sensor that is arranged before and after the variable resistor and that detects a change in temperature due to the variable resistor. A refrigeration apparatus comprising a second temperature sensor. 3. A refrigerating apparatus for circulating a single refrigerant or a non-azeotropic mixed refrigerant composed of a high boiling point refrigerant and a low boiling point refrigerant to a heat exchanger, the refrigeration apparatus being arranged at an outlet of the heat exchanger, A resistor that gives flow resistance to the refrigerant when it acts as a condenser, and a first temperature sensor and a second temperature sensor that are arranged in front of and behind the resistor to detect temperature changes by the resistor. And a flow rate control valve that controls the flow rate of the refrigerant according to the detection values of the first and second temperature sensors.